US5646884AExpiredUtility

Electrical data storage device

44
Assignee: TEXAS INSTRUMENTS INCPriority: Aug 5, 1995Filed: Jun 26, 1996Granted: Jul 8, 1997
Est. expiryAug 5, 2015(expired)· nominal 20-yr term from priority
Inventors:Jan Paul Anthonie Van Der Wagt
G11C 11/56G11C 2211/5614B82Y 10/00
44
PatentIndex Score
9
Cited by
6
References
25
Claims

Abstract

A data storage device consisting of at least two series connected resonant tunneling diodes (RTD1, RTD2) with capacitors (C1 ,C2) coupled thereacross. By coupling a time varying voltage V(t) across the series connected diodes, one the diodes can be selectively switched from a state below its peak current to a stable point above its peak current. The diode which switches state is controlled by the slope of the time varying voltage V(t). Cells consisting of at least two or more resonant tunneling diodes may be connected in series and can store up to 2 N binary states where N is the number of resonant tunneling diodes in the cell.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
       1. An electrical data storage device comprising: a first negative impedance device having a first peak current whereat said first negative impedance device switches from one stable state to another stable state;   a second negative impedance device connected in series with said first negative impedance device, said second negative impedance device having a second peak current whereat said second negative impedance switches from one stable state to another stable state, said second peak current being greater than said first peak current;   a first capacitance coupled across said first negative impedance device;   a second capacitance coupled across said second negative impedance device, the magnitude of said second capacitance being smaller than the magnitude of said first capacitance; and   a power source coupled across said first and second negative impedance devices for producing a ramp voltage with one of two different slopes for the leading edge of said ramp voltage, the first slope being operative to switch said first negative impedance device and the second slope being operative to switch said second negative impedance device.   
     
     
       2. The electrical data storage device of claim 1 wherein said first and second negative impedance devices each comprise a resonant tunneling diode. 
     
     
       3. The electrical data storage device of claim 1 additionally including a first voltage sensor across said first negative impedance device for sensing the voltage thereacross and a second voltage sensor across said second negative impedance device for sensing the voltage thereacross. 
     
     
       4. An electrical data storage device comprising: at least two negative impedance devices coupled in series, each negative impedance device having a different peak current whereat said negative impedance device switches state; and   a capacitance coupled across each said negative impedance device, the negative impedance device having the lowest peak current having the greatest capacitance thereacross and the negative impedance device having the highest peak current having the smallest capacitance thereacross.   
     
     
       5. The data storage device of claim 4 wherein each said negative impedance device comprises a resonant tunneling diode. 
     
     
       6. The storage device of claim 4 additionally comprising a power source coupled across said series connected negative impedance devices, said power source producing a step-like voltage across said negative impedance devices including a leading edge which has a slope selected to switch a unique one of said series connected negative impedance devices. 
     
     
       7. The storage device of claim 4 additionally including a plurality of voltage sensors, each coupled across a unique one of said negative impedance devices to detect the state of each said negative impedance device. 
     
     
       8. The storage device of claim 4 additionally comprising a power source coupled across said series connected negative impedance devices to produce a staircase voltage where each step of said staircase voltage has a different slope for its leading edge which is selected to switch a unique one of said negative impedance devices. 
     
     
       9. The storage device of claim 4 additionally comprising a power source coupled across said series connected negative impedance devices to produce a DC component sufficient to maintain each negative impedance device at its operating state and to produce an AC component to selectively switch the operating state of and selected negative impedance device from a state below its peak current point on its I/V curve to a point above its peak current on its I/V curve. 
     
     
       10. An electrical data storage device comprising: at least two negative impedance devices coupled in series, each negative impedance device having a different peak current whereat said negative impedance device switches between two stable states;   a capacitance coupled across each said negative impedance device with no two capacitances being the same, the capacitances being arranged so that the negative impedance device having the lowest peak current has the greatest capacitance thereacross and the negative impedance device having the highest peak current has the smallest capacitance thereacross; and   a power source coupled across said series connected negative impedance devices supply DC power to maintain said series connected negative impedance devices at any one of the stable states thereof and to selectively supply an AC power pulse to said series connected negative impedance devices having a selected slope for the leading edge thereof to switch a selected one of said negative impedance devices from a first state on the IN curve thereof below the peak current point to a second state on the IN curve above the peak current point.   
     
     
       11. The storage device of claim 10 wherein the negative impedance device controlled by said AC power is selected by the slope of the AC power supplied thereto. 
     
     
       12. The storage device of claim 10 wherein said negative impedance devices each comprise a resonant tunneling diode. 
     
     
       13. The storage device of claim 10 additionally including a plurality of voltage sensors, each coupled across a unique one of said negative impedance devices to the state of each said negative impedance device. 
     
     
       14. The storage device of claim 1 wherein each said capacitance comprise the capacitance of each said negative impedance device. 
     
     
       15. The storage device of claim 4 wherein each said capacitance comprises the capacitance of the negative impedance device itself. 
     
     
       16. The storage device of claim 10 wherein each said capacitance comprises the capacitance of the negative impedance device itself. 
     
     
       17. An electrical data storage device comprising: at least two negative impedance devices coupled in series, each negative impedance device having a different peak current whereat said negative impedance device switches between two stable states;   a capacitance coupled across each said negative impedance device with no two capacitances being the same, the capacitances being arranged so that the negative impedance device having the lowest peak current has the greatest capacitance thereacross and the negative impedance device having the highest peak current has the smallest capacitance thereacross; and   a current source coupled in series with said series connected negative impedance devices supply DO power to maintain said series connected negative impedance devices at any one of the stable states thereof; and   an AC power supply to said series connected negative impedance devices at the point of connection with said current source, said AC power supply producing a pulse having a selected slope for the leading edge thereof to switch a selected one of said negative impedance devices from a first state on the I/V curve thereof below the peak current point to a second state on the IN curve above the peak current point.   
     
     
       18. The storage device of claim 17 wherein said AC power supply includes an isolation capacitor coupled at one lead thereof to the connection point between said series connected negative impedance devices and said current source, the other lead of said capacitor being coupled to a node; a word line and a bit line, said word line for receiving a pulse beginning at time T1 and ending at time T3 having one of n voltages thereon where n is the number of negative impedance devices in said storage device, said bit line for receiving a pulse beginning at time T2 and ending at time T4 where T1<T2<T3<T4; and   a FET transistor with a gate and two controlled leads, said gate being coupled to said word line, one said controlled lead is coupled to said bit line and said other controlled lead is coupled to said node.   
     
     
       19. The storage device of claim 18 wherein said negative impedance devices each comprise a resonant tunneling diode. 
     
     
       20. The storage device of claim 18 additionally including a plurality of voltage sensors, each coupled across a unique one of said negative impedance devices to determine the state of each said negative impedance device. 
     
     
       21. The storage device of claim 17 wherein each said capacitance comprises the capacitance of each said negative impedance device. 
     
     
       22. The storage device of claim 18 wherein each said capacitance comprises the capacitance of the negative impedance device itself. 
     
     
       23. The data storage device of claim 4 wherein each said negative impedance device comprises a tunnel diode. 
     
     
       24. The data storage device of claim 10 wherein each said negative impedance device comprises a tunnel diode. 
     
     
       25. The data storage device of claim 1 wherein each said negative impedance device comprises a tunnel diode.

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